Mobile station, base station, communication system, and communication method

ABSTRACT

A scrambler performs IQ multiplexing of output signals from a spreader and a distributor in order to generate a complex signal (I signal and Q signal), amplitude coefficients βcc(I) and βcc(Q) are determined in accordance with signal powers on I axis and Q axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims the benefit of priorityunder 35 U.S.C. §120 from U.S. Ser. No. 11/980,445 filed Oct. 31, 2007,which is a division of U.S. Ser. No. 11/033,824 filed Jan. 13, 2005,which is a division of U.S. Ser. No. 10/472,493 filed Sep. 30, 2003 (nowU.S. Pat. No. 7,289,423 issued Oct. 30, 2007), which is a National Stageof PCT/JP02/08435 filed Aug. 21, 2002 and is based upon and claims thebenefit of priority from Japanese Patent Application No. 2002-20465filed Jan. 29, 2002, the entire contents of all of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a mobile station, a base station, acommunication system, and a communication method which are capable ofperforming data communication with high speed.

BACKGROUND ART

The ITU (International Telecommunication Union) has adopted pluralwireless communication methods called the 3^(rd) generation as IMT-2000for mobile wireless communication method typically used in the field ofcellular phones. In Japan W-CDMA (Wideband Code Division MultipleAccess) method as one of them is commercially available from 2001.

W-CDMA is made to obtain a communication speed of the maximum 2 Mbps(bit per second) per mobile station. The 3GPP (3^(rd) GenerationPartnership Project) as one of standardization groups has determined thespecification of the first edition as Release 99 version (Release 1999)which was summarized at 1999.

FIG. 1 is a general schematic diagram of a conventional communicationsystem. In FIG. 1, reference number 1 designates a base station, and 2denotes a mobile station performing a wireless communication with thebase station 1. Reference number 3 indicates a downlink for use in datatransmission from the base station 1 to the mobile station 2, and 4indicates an uplink for use in data transmission from the mobile station2 to the base station 1.

FIG. 2 is a diagram showing an internal configuration of the mobilestation 2. In FIG. 2, reference number 11 designates a distributor fordistributing data DPDCH of a dedicated data channel (Dedicated PhysicalData Channel) in parallel and outputting obtained data DPDCH1-DPDCH6 ofplural data channels. Reference number 12 denotes a spreader forperforming a spread spectrum process for data DPDCH1-DPDCH6 output fromthe distributor 11 and control data DPCCH of a control channel(Dedicated Physical Control Channel). The spreader 12 multiplies thedata DPDCH1-DPDCH6 and the control data DPCCH by spreading codes forchannel separation.

Reference number 13 indicates a scrambler for generating a complexsignal (I signal: Inphase signal, Q signal: Quadrature signal) byperforming IQ multiplexing for output signals from the spreader 12.Reference number 14 denotes a modulator for generating a modulatedsignal by performing orthogonal modulation of a complex signal (I signaland Q signal) generated at the scrambler 13. Reference number 15indicates a frequency converter for converting in frequency themodulated signal generated at the modulator 14 to a radio frequencysignal. Reference number 16 designates an antenna for transmitting theradio frequency signal output from the frequency converter 15.

FIG. 3 is a diagram showing an internal configuration of the spreader 12and the scrambler 13. In FIG. 13, reference numbers 21 to 26 indicatemultipliers for multiplying the data DPDCH1-DPDCH6 output from thedistributor 11 by spreading codes Cd,1 to Cd,6 for use in channelseparation. Reference numbers 27 designates a multiplier for multiplyingthe control data DPCCH of the control channel by a spreading code Cc foruse in channel separation. Reference number 31 to 36 denote multipliersfor multiplying the output signals from the multipliers 21 to 26 by anamplitude coefficient βd for the data DPDCH. Reference number 37designates a multiplier for multiplying the output signal from themultiplier 27 by an amplitude coefficient βc for the control data DPCCH.

Reference number 38 denotes an adder for adding the output signals fromthe multipliers 31 to 33, and 39 denotes an adder for adding the outputsignals from the multipliers 34 to 37,

Reference number 40 denotes a multiplier for multiplying the outputsignal from the adder 39 by imaginary number “j”, 41 indicates adder foradding the output signals from the adder 38 and the multiplier 40.Reference number 42 designates a multiplier for multiplying the outputsignal from the adder 41 by an identification code Sdpch,n for acellular station in order to generate the complex signal (I signal and Qsignal), and then outputting the generated complex signal.

Next, a description will be given of the operation of the conventionalcommunication system in which data are transmitted from the mobilestation 2 to the base station 1.

When transmitting data to the base station 1, as shown in FIG. 1, themobile station 2 uses the uplink 4 for the transmission data. In W-CDMAstandard, when using the uplink 4, the mobile station 2 can use maximumsix channels for the transmission data according to a communicationspeed required in communication service.

In the following explanation, data on six data channels and control datafor one control channel are transmitted for brief explanation.

First, the distributor 11 in the mobile station 2 distributes the dataDPDCH of the dedicated data channel in parallel and outputs the dataDPDCH1-DPDCH6 for the plural data channels.

When the distributor 11 outputs the data DPDCH1-DPDCH6 for the pluraldata channels, the multipliers 21-26 in the spreader 12 multiply thesedata DPDCH1-DPDCH6 with the spreading codes Cd,1-Cd,6 for channelseparation. The multiplier 27 in the spreader 12 multiplies the controldata DPCCH for the control channel by the spreading code Cc for channelseparation.

The scrambler 13 performs IQ multiplexing for the output signal from thespreader 12 in order to generate the complex signal (I signal and Qsignal).

That is, the multipliers 31-36 in the scrambler 13 multiply the outputsignals from the multipliers 21-26 in the spreader 12 by the amplitudecoefficient βd. The multiplier 37 in the scrambler 13 multiplies theoutput signal from the multiplier 27 by the amplitude coefficient βc forthe control data DPCCH.

FIG. 4 is a diagram showing a table of possible values of the amplitudecoefficients βc and βd.

The amplitude coefficients βd and βc are coefficients for use in thedetermination of a power ratio between the data DPDCH1-DPDCH6 and thecontrol data DPCCH, which have been defined in TS25.213 v3.6.0 (2001June) Release 1999 in 3GPP standard. Right side in this table shows thepossible values of the amplitude coefficients βc and βd.

The adder 38 in the scrambler 13 adds the output signals from themultipliers 31-33 and the adder 39 in the scrambler 13 adds the outputsignals from the multipliers 34-37.

The multiplier 40 in the scrambler 13 multiplies the output signal fromthe adder 39 by imaginary number “j” so as to assign the output signalfrom the adder 39 to Q axis.

The data DPDCH1, DPDCH3, and DPDCH5 are assigned on I axis and the dataDPDCH2, DPDCH4, and DPDCH6 are assigned on Q axis. TS25.213 in 3GPPstandard defines how to assign data channels on I axis/Q axis.

Next, the adder 41 in the scrambler 13 adds the output signals from theadder 38 and the multiplier 40. The multiplier 42 in the scrambler 13multiplies the output signal from the adder 41 by an identification codeSdpch,n to be used to identify a dedicated mobile station, and thenoutputs the complex signal (I signal and Q signal).

When the scrambler 13 generates the complex signal (I signal and Qsignal) in such a manner described above, the modulator 14 performs theorthogonal modulation for the complex signal (I signal and Q signal) soas to generate the modulated signal.

When the modulator 14 generates the modulated signal, the frequencyconverter 15 converts this modulated signal in frequency, generates theradio frequency signal, and amplifies and outputs the generated one tothe antenna 16. Through the antenna 16 the radio frequency signal istransmitted to the base station 1.

When receiving the radio frequency signal transmitted from the mobilestation 2, the base station 1 performs inverse processes to theprocesses in the mobile station 1 in order to obtain the necessary data.

The above conventional case has explained the case to set the six datachannels. When the set number of the data channels is not more than 5,no process for unnecessary data channel is performed because the dataare assigned on I axis and Q axis in the order of increasing datanumber, for example, the data DPDCH1 is firstly assigned and the dataDPDCH2 is then assigned. The set number of the data channels isdetermined based on the communication service and the communicationspeed.

FIG. 5 is a diagram showing a complex plane of only one data channel.

In this case, the data DPDCH1 for the data channel is assigned on I axisand the control data DPCCH for the control channel is assigned on Qaxis. Because the data DPDCH1 and the control data DPCCH are orthogonalto each other, the base station 1 can separate the received data inchannel and then demodulate the separated data.

It is possible to perform the same operation for the case where the setnumber of the data channels is 2, 3, 4, 5, or 6. In this case, thechannel component in the same axis can be separated using the spreadingcode for channel separation.

The above conventional example has described the case to set thedownlinks 3 and the uplink 4 between the base station 1 and the mobilestation 2. In order to achieve a further high speed data communicationin the downlink from the base station 1 to the mobile station 2, HSDPA(High Speed Downlink Packet Access) has been proposed and examined (seeTR25.858 v1.0.0 (2001 June) “High Speed Downlink Packet Access: PhysicalLayer Aspects (Release 5)”.

FIG. 6 shows HSDPA in which a new downlink 5 is added in addition to thedownlink 3 in the conventional case.

In the addition of the new downlink 5, it has been examined that themobile station 2 transmits a response data (ACK/NACK) and the like tothe high speed packet data in the downlink to the base station 1.However, as shown in FIG. 6 in which the response data (ACK/NACK) istransmitted through the exclusive control channel (as the uplink channel6). Through the exclusive control channel the response data areseparated and identified using the spreading code for channelseparation, like the same manner for the conventional control channel,and then added and multiplexed in the conventional uplink 4. TR25.858defines to describe “additional DPCCH” as the exclusive control channel.

Because the conventional communication system has the configurationdescribed above, it is necessary to assign the additional exclusivecontrol channel on I axis and Q axis. This causes a drawback where adistortion is generated at the built-in orthogonal modulator (ororthogonal modulator and amplifier) in the modulator 14 in the mobilestation 2 because nonlinear section of input/output characteristic mustbe used, when the peak power of I axis or Q axis is increased byassigning the exclusive control channel to I axis or Q axis, forexample.

When the balance between the signal powers of I axis and Q axis isdecayed, the peak power of the modulated signal output from themodulator 14 after the orthogonal modulation is greater than the peakpower of the modulated signal of the case where the signal powers of Iaxis and Q axis are in balance. For example, in case an amplifierincorporated in the frequency converter 15 in the mobile station 2amplifies the radio frequency signal, a distortion occurs because theamplifier uses in amplification a non-linear part of the input/outputcharacteristic thereof. When the non-linear component in the distortiongenerated in the amplifier is output, this non-linear component and thesignal component of the frequency band adjacent to this linear componentinterfere to each other. The reception of the adjacent frequency band isthereby disturbed by jamming.

The present invention is made to overcome the above drawbacks. It is anobject of the present invention is to provide a mobile station, a basestation, a communication system, and a communication method which arecapable of suppressing the generation of a distortion in amplifiers andthereby to suppress the occurrence of jamming in the adjacent frequencyband.

DISCLOSURE OF INVENTION

In carrying out the invention and according to one aspect thereof, thereis provided a mobile station capable of generating a complex signal bydistributing control data of an additional control channel on I axis andQ axis, and performing IQ multiplexing for them in the case of addingcontrol data of an additional control channel.

It is thereby possible to suppress the generation of a distortion in anamplifier and thereby to suppress the occurrence of jamming in theadjacent frequency band.

The mobile station according to the present invention distributes thecontrol data for the additional control channel on I axis and Q axis inconsideration of a signal power of I axis and a signal power of Q axisin the case of adding control data of an additional control channel.

It is thereby possible to suppress the generation of a distortion in theamplifier and thereby to suppress the occurrence of jamming in theadjacent frequency band.

The mobile station according to the present invention distributes thecontrol data for the additional control channel on I axis and Q axis sothat the signal power of I axis becomes equal to that of Q axis in thecase of adding control data of an additional control channel.

It is thereby possible to suppress the generation of a distortion in theamplifier efficiently.

The mobile station according to the present invention assigns thecontrol data for the additional control channel to one axis whose signalpower is smaller than that of the other axis in I axis and Q axis in thecase of adding control data of an additional control channel.

It is thereby possible to suppress the generation of a distortion in theamplifier with a simple configuration.

The mobile station according to the present invention assigns thecontrol data for the additional control channel on Q axis when thenumber of data channels is an odd number, and assigns the control dataon Q axis when it is an even number, in the case of adding control dataof an additional control channel.

It is thereby possible to suppress the generation of a distortion in theamplifier with a simple configuration.

The mobile station according to the present invention assigns thecontrol data for the additional control channel on Q axis in the case ofadding control data of an additional control channel.

It is thereby possible to suppress the generation of a distortion in theamplifier and to have a circuit with a simple configuration.

A base station according to the present invention synthesizes controldata for an additional control channel distributed on I axis and Q axisand outputs the synthesized one, when the control data for theadditional control channel are distributed on I axis and Q axis.

It is thereby possible to suppress the generation of a distortion in theamplifier and to suppress the occurrence of jamming in the adjacentfrequency band.

A communication system according to the present invention, in the caseof adding control data of an additional control channel, IQ multiplexingmeans distributes the control data for the additional control channel onI axis and Q axis, performs IQ multiplexing, and outputs a complexsignal. Further, IQ separation means in a base station synthesizes thecontrol data for the additional control channel distributed on I axisand Q axis and outputs the synthesized one when the control data for theadditional control channel are distributed on I axis and Q axis.

It is thereby possible to suppress the generation of a distortion in theamplifier and thereby to suppress the occurrence of jamming in theadjacent frequency band.

A communication method according to the present invention has thefollowing steps in a case to add the control data for the additionalcontrol channel. In a mobile station, control data for an additionalcontrol channel are distributed on I axis and Q axis, IQ multiplexing isperformed in order to generate a complex signal. In a base station, thecontrol data distributed on I axis and Q axis are synthesized and outputwhen the control data for the additional control channel are distributedon I axis and Q axis.

It is thereby possible to suppress the generation of a distortion in theamplifier and thereby to suppress the occurrence of jamming in theadjacent frequency band.

Other objects, features and advantages of the present invention willbecome apparent in the following description and appended drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic diagram of a conventional communication system;

FIG. 2 is a diagram showing an internal configuration of a mobilestation;

FIG. 3 is a diagram showing an internal configuration of a spreader anda scrambler;

FIG. 4 is diagram showing a table of possible values of the amplitudecoefficients βc and βd;

FIG. 5 is a diagram showing a complex plane in case of one data channel;

FIG. 6 is a schematic diagram showing a conventional communicationsystem;

FIG. 7 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a first embodiment ofthe present invention;

FIG. 8 is a diagram showing a configuration of a base station applicableto a communication system according to the first embodiment of thepresent invention;

FIG. 9 is a diagram showing an internal configuration of a spreader, adistributor, and a scrambler;

FIG. 10 is a diagram showing an internal configuration of a descrambler,a despreader, and a synthesizer;

FIG. 11 is a flowchart showing a communication method according to afirst embodiment of the present invention;

FIG. 12 is a diagram showing a complex plane in case of one datachannel;

FIG. 13 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a second embodiment ofthe present invention;

FIG. 14 is a diagram showing a configuration of a base stationapplicable to a communication system according to the second embodimentof the present invention;

FIG. 15 is a diagram showing a complex plane in case of one datachannel;

FIG. 16 is a diagram showing a complex plane in case of two datachannels;

FIG. 17 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a third embodiment ofthe present invention;

FIG. 18 is a diagram showing a configuration of a base stationapplicable to a communication system according to the third embodimentof the present invention;

FIG. 19 is a diagram showing a complex plane in case of one datachannel;

FIG. 20 is a diagram showing a complex plane in case of two datachannels;

FIG. 21 is a diagram showing CCDF characteristic of a modulatedwaveform;

FIG. 22 is a diagram showing CCDF characteristic of a modulatedwaveform;

FIG. 23 is a diagram showing CCDF characteristic of a modulatedwaveform;

FIG. 24 is a diagram showing CCDF characteristic of a modulatedwaveform;

FIG. 25 is a diagram showing CCDF characteristic of a modulatedwaveform; and

FIG. 26 is a diagram showing CCDF characteristic of a modulatedwaveform.

BEST MODE FOR CARRYING OUT THE INVENTION

The best mode for carrying out the invention will now be described indetail with reference to the accompanying drawings.

First Embodiment

FIG. 7 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a first embodiment ofthe present invention. In FIG. 7, reference number 51 designates adistributor for distributing data DPDCH in parallel and the outputtingthe distributed data DPDCH1-DPDCH6 in plural data channels. Referencenumber 52 denotes a spreader for performing a spread spectrum processesfor the data DPDCH1-DPDCH6 output from the distributor 51 and controldata DPCCH and ADPCCH (additional DPCCH) of control channels bymultiplying those data DPDCH1-DPDCH6, and control data DPCCH and ADPCCHby spreading codes for use in channel separation.

Reference number 53 indicates a distributor for distributing the controldata ADPCCH after the spread spectrum process performed by the spreader52.

Reference number 54 indicates a scrambler for generating a complexsignal (I signal and Q signal) by performing IQ multiplexing for theoutput signals from the spreader 52 and the distributor 53.

The IQ multiplexing means consists of the distributor 51, the spreader52, the distributor 53, and the scrambler 54.

Reference number 55 denotes a modulator for generating a modulatedsignal by performing orthogonal modulation of the complex signal (Isignal and Q signal) generated at the scrambler 54. Reference number 56indicates a frequency converter for converting in frequency themodulated signal generated at the modulator 55 to a radio frequencysignal. Reference number 57 designates an antenna for transmitting theradio frequency signal output from the frequency converter 56.

The transmitting means consists of the modulator 55, the frequencyconverter 56, and the antenna 57.

FIG. 8 is a diagram showing a configuration of a base station applicableto the communication system according to the first embodiment of thepresent invention. In FIG. 8, reference number 61 designates an antennafor receiving the radio frequency signal transmitted from the mobilestation 2, and 62 denotes a frequency converter for converting infrequency the radio frequency signal received through the antenna 61 toa base band signal and outputting the obtained base band signal.Reference number 63 indicates an orthogonal demodulator for performingorthogonal demodulation for the base band signal transmitted from thefrequency converter 62 and outputting a complex signal (I signal and Qsignal).

The receiving means consists of the antenna 61, the frequency converter62, and the orthogonal demodulator 63.

Reference number 64 designates a descrambler for multiplying the complexsignal (I signal and Q signal) transmitted from the orthogonaldemodulator 63 by an identification code to identify the mobile station2 from other mobile stations. Reference number 65 indicates a despreaderfor multiplying the output signal from the descrambler 64 by a spreadingcode for use in channel separation in order to separate data of eachchannel. Reference number 66 designates a data channel synthesizer forsynthesizing the data DPDCH1-DPDCH6 for the data channels in order toreconstruct the data DPDCH of the dedicated data channel. Referencenumber 67 indicates a synthesizer for synthesizing the control dataADPCCH for the control channel distributed on I axis and Q axis.

The IQ separation means consists of the descrambler 64, the despreader65, the data channel synthesizer 66, and the synthesizer 67.

FIG. 9 is a diagram showing an internal configuration of the spreader52, the distributor 53, and the scrambler 54. In FIG. 9, referencenumbers 71 to 76 designate multipliers for multiplying the dataDPDCH1-DPDCH6 output from the distributor 51 by spreading codes Cd,1 toCd, 6 for use in channel separation. Reference number 77 denotes amultiplier for multiplying the control data DPCCH for the controlchannel by the spreading code Cc for use in channel separation.Reference number 78 designates a multiplier for multiplying control dataADPCCH for an additional control channel to be newly added by aspreading code Ccc for use in channel separation. Reference numbers 81to 86 denote multipliers for multiplying the output signals from themultipliers 71 to 76 by an amplitude coefficient βd for the data DPDCH,87 indicates a multiplier for multiplying the output signal from themultiplier 77 by an amplitude coefficient βc for the data DPCCH, and 88and 89 designate multipliers for multiplying the output signal from thedistributor 53 by the amplitude coefficient βcc for use in the controldata ADPCCH.

Reference number 90 designates an adder for adding the output signalsfrom the multipliers 81-83 and 88. Reference number 91 designates anadder for adding the output signals from the multipliers 84-87 and 89.

Reference number 92 designates a multiplier for multiplying the outputsignal from the adder 91 by imaginary number “j”, 93 denotes an adderfor adding the output signal from the adder 90 and the output signalfrom the multiplier 92 together.

Reference number 94 indicates a multiplier for multiplying the outputsignal from the adder 93 by an identification code Sdpch,n to identifyone mobile station from others, and then outputting the generatedcomplex signal (I signal, Q signal).

FIG. 10 is a diagram showing an internal configuration of thedescrambler 64, the despreader 65, and the synthesizer 67. In FIG. 10,reference number 100 designates multipliers for multiplying the complexsignal (I signal and Q signal) output from the descrambler 64 by theidentification code Sdpch,n. Reference numbers 101-104 denotemultipliers for multiplying the I signal output from the descrambler 64by each spreading code Cd,1, Cd,3, Cd,5, and Ccc for use in channelseparation.

Reference numbers 105-109 indicate multipliers for multiplying the Qsignal output from the descrambler 64 by each of spreading codes Cd,2,Cd,4, Cd,6, Cc, and Ccc for use in channel separation. Reference number110-118 designate integrators for integrating in time the output signalsfrom the multipliers 101-119 along the time length of the spreadingcode.

FIG. 11 is a flowchart showing a communication method according to thefirst embodiment of the present invention.

Next, a description will be given of the operation to transmit data fromthe mobile station 2 to the base station 1, where the data include thedata of six data channels and the control data of two control channels,for brief explanation.

First, the distributor 51 in the mobile station 2 distributes the dataDPDCH for the dedicated data channel in parallel, and outputs the dataDPDCH1-DPDCH6 for plural data channels (Step ST1).

When the distributor 51 outputs the data DPDCH1-DPDCH6 for the pluraldata channels, the spreader 52 performs the spread spectrum bymultiplying the data DPDCH1-DPDCH6 for the plural data channels and thecontrol data DPCCH and ADPCCH for the control data channels by spreadingcodes (Step ST2).

That is, the multipliers 71-76 in the spreader 52 multiply the dataDPDCH1-DPDCH6 for the plural data channels output from the distributor51 by the spreading codes Cd,1-Cd,6 for use in channel separation.

The multiplier 77 in the spreader 52 multiplies the control data DPCCHfor the control channel by the spreading code Cc for use in channelseparation. The multiplier 78 in the spreader 52 multiplies the controldata ADPCCH for the additional control channel to be newly added by thespreading code Ccc for use in channel separation.

The distributor 53 distributes the output data from the multiplier 78 tothe multipliers 88 and 89 in the scrambler 54 after the multiplier 78 inthe spreader 52 multiplies the control data ADPCCH for the additionalcontrol channel by the spreading code Ccc for use in channel separation(Step ST3).

The distribution ratio for the multipliers 88 and 89 performed by thescrambler 54 is 1:1 in this example. However, it is possible todetermine another distribution ratio based on signal powers of I axisand Q axis.

The scrambler 54 performs IQ multiplexing of the output signal in orderto generate the complex signal (I signal and Q signal) (Step ST4).

That is, the multipliers 81-86 in the scrambler 54 multiply the outputsignals from the multipliers 71-76 by the amplitude coefficient βd forthe data DPDCH. The multiplier 87 in the scrambler 54 multiplies theoutput signal from the multiplier 77 by the amplitude coefficient βc forthe data DPCCH.

The multiplier 88 in the scrambler 54 multiplies the output signal fromthe distributor 53 by the amplitude coefficient βcc(I) for the dataADPCCH. The multiplier 89 in the scrambler 54 multiplies the outputsignal from the distributor 53 by the amplitude coefficient βcc(Q) forthe data ADPCCH.

By the way, the amplitude coefficients βcc(I) and βcc(Q) for the controldata ADPCCH are determined in accordance with the signal powers of Iaxis and Q axis. That is, they are determined so that the signal powerof I signal becomes equal to the signal power of the Q signal, both thesignal powers will be output from the scrambler 54.

In this example, FIG. 12 shows the complex plane of one data channel.For example, when the signal power of the data DPDCH1 is “1.5” and thesignal power of the control data DPCCH is “1.0”, the amplitudecoefficients βcc(I) and βcc(Q) are determined so that the signal powerof the control data ADPCCH(I) in I axis becomes “1.0” and the signalpower of the control data ADPCCH(Q) in Q axis becomes “0.5”.

Next, the adder 90 in the scrambler 54 adds the output signals from themultipliers 81-83 and 88 together, and the adder 91 in the scrambler 54adds the output signals from the multipliers 84-87 and 89 together.

The multiplier 92 in the scrambler 54 multiplies the output signal fromthe adder 91 by imaginary number “j” in order to assign the outputsignal from the adder 91 on Q axis.

Next, the adder 93 in the scrambler 54 adds the output signals from theadder 90 and the multiplier 92, and the multiplier 94 in the scrambler54 multiplies the output signal from the adder 93 by the identificationcode Sdpch,n in order to output the complex signal (I signal and Qsignal).

When receiving the complex signal (I signal and Q signal) from thescrambler 54, the modulator 55 performs orthogonal modulation for thereceived complex signal (I signal and Q signal) in order to generate themodulated signal. (Step ST5)

When the modulator 55 generates the modulated signal, the frequencyconverter 56 converts in frequency the modulated signal to the radiofrequency signal, and outputs the converted one to the antenna 57 (StepST6). Through the antenna 57 the radio frequency signal is transmittedto the base station 1.

When receiving the radio frequency signal transmitted from the mobilestation 2 through the antenna 61, the frequency converter 62 in the basestation 1 converts in frequency the received one in order to generatethe base band signal (Step ST7).

When receiving the base band signal from the frequency converter 62, theorthogonal demodulator 63 performs orthogonal demodulating for the baseband signal in order to generate the complex signal (I signal and Qsignal) (Step ST8).

When receiving the complex signal (I signal and Q signal) from theorthogonal demodulator 63, the descrambler 64 multiplies the receivedcomplex signal (I signal and Q signal) by the identification code inorder to distinguish the target mobile station from other stations (StepST9). That is, the multiplier 100 in the descrambler 64 multiplies thecomplex signal (I signal and Q signal) output from the orthogonaldemodulator 63 by the identification code Sdpch,n for the mobile stationidentification.

The despreader 65 multiplies the output signal from the descrambler 64by the spreading code for channel separation in order to separate thedata of each channel (Step ST10). That is, the multipliers 101-104 inthe despreader 65 multiply the I signal output from the descrambler 64by the spreading codes Cd,1, Cd,3, Cd,5, and Ccc. The multipliers105-109 in the despreader 65 multiply the Q signal output from thedescrambler 64 by the spreading codes Cd,2, Cd,4, Cd,6, Cc, and Ccc forchannel separation.

The integrators 110-118 in the despreader 65 integrate the outputsignals from the multipliers 101-109 along the spreading code timelength in order to reconstruct the data DPDCH1-DPDCH6 for the datachannels and the control data DPCCH for the control channel.

The data channel synthesizer 66 synthesizes the data DPDCH1-DPDCH6 forthe data channels in order to reconstruct the data DPDCH for thededicated data channel (Step ST11).

The adder 67 adds the output signals from the integrators 113 and 118 inthe despreader 65, so that the control data ADPCCH for the additionalcontrol channel to be newly added can be reconstructed (Step ST12).

As has been apparently understood by the above description, according tothe first embodiment, when the scrambler 54 performs IQ multiplexing ofthe output signals of the spreader 52 and the distributor 53 in order togenerate the complex signal (I signal and Q signal), the amplitudecoefficients βcc(I) and βcc(Q) for the data ADPCCH are determined inaccordance with the signal powers of I axis and Q axis. It is therebypossible to suppress a distortion caused in the amplifier in thefrequency converter 56, so that the occurrence of jamming in theadjacent frequency band can be suppressed.

The first embodiment has designed to allocate the six data channels. Thepresent invention is not limited by this case, when the allocated numberof data channels is not more than five, the data DPDCH1 is firstlyassigned on I axis/Q axis and the remained data are then assigned on Iaxis/Q axis in order. That is, no process for unnecessary data channelis performed. The allocated number of the data channels is determinedbased on necessary communication service such as a communication speed.

Second Embodiment

FIG. 13 is a diagram showing a configuration of a mobile stationapplicable to a communication system according to a second embodiment ofthe present invention. FIG. 14 is a diagram showing a configuration of abase station which is applicable to the communication system accordingto the second embodiment of the present invention. In those FIGS. 13 and14, the same components of the first embodiment shown in FIGS. 7 and 8will be referred with the same reference numbers and the explanation ofthem is omitted here.

Reference number 58 designates a selector (IQ multiplexing means) foroutputting the control data ADPCCH for the control channel after spreadspectrum to one of the multipliers 88 and 89 in the scrambler 54.Reference number 68 designates a selector (IQ separation means) forinputting and then outputting the control data ADPCCH for the controlchannel transferred from one of the integrators 113 and 118 in thedescrambler 64.

The first embodiment has previously described the case in which thedistributor 53 distributes the output signals from the multiplier 78 inthe spreader 52 to the multipliers 88 and 89 in the scrambler 54, andthe multipliers 88 and 89 in the scrambler 54 multiply the output signalfrom the distributor 53 by the amplitude coefficients βcc(I) and βcc(Q)so that the signal power of I signal becomes equal to the signal powerof Q signal. In the second embodiment it is possible that the selector58 outputs the output signal of the multiplier 78 in the spreader 52 tothe multipliers 88 or 89 in the scrambler 54 in consideration of thesignal powers of I axis and Q axis in order to assign the control dataADPCCH for the control channel to one axis of a smaller signal power inI axis and Q axis.

That is, TS25.213 as 3GPP standard has defined that data of data channelare assigned on I axis when the set number of data channels is one (seeFIG. 15), and data for each data channel are assigned on I axis and Qaxis when two (see FIG. 16). That is, the data of the data channels areassigned on I axis and Q axis, alternately.

In the second embodiment, in order to keep the balance of the signalpower of I axis and the signal power of Q axis, the selector 58 in themobile station 2 outputs the output data of the multiplier 78 to themultiplier 89 in the scrambler 54 when the set number of the datachannels is an odd number so that the control data ADPCCH of the controlchannel are assigned on Q axis.

In order to obtain the control data ADPCCH of the control channelassigned on Q axis, the selector 68 in the base station 1 inputs thecontrol data ADPCCH of the control channel transferred from theintegrator 118 in the descrambler 64 and outputs the control dataADPCCH.

On the other hand, the selector 58 in the mobile station 2 outputs theoutput data of the multiplier 78 in the spreader 52 to the multiplier 88in the scrambler 54 when the set number of the data channels is an evennumber so that the control data ADPCCH of the control channel areassigned on I axis.

In order to obtain the control data ADPCCH of the control channelassigned on I axis, the selector 68 in the base station 1 inputs thecontrol data ADPCCH of the control channel transferred from theintegrator 113 in the descrambler 64 and outputs the control dataADPCCH.

As described above, according to the second embodiment, like the effectof the first embodiment, it is possible to suppress the generation of adistortion in the amplifier in the frequency converter 56 and therebypossible to suppress the occurrence of jamming in the adjacent frequencyband, for example.

The above second embodiment has descried the case where the axis onwhich the control data of the control channel are assigned is determinedbased on the set number of the data channels. The present invention isnot limited by this case, for example, it is possible that the selector58 in the mobile station 2 determines the axis on which the control dataADPCCH of the control channel are assigned based on the measured signalpowers of I axis and Q axis.

Third Embodiment

The second embodiment has shown the case in which the control dataADPCCH of the control channel are assigned on one axis of a smallersignal power in I axis and Q axis. Like the third embodiment, it ispossible to assign the control data ADPCCH of the control channel onlyon Q axis, as shown in FIG. 19 and FIG. 20.

That is, it can be considered that a spreading code length of thecontrol data ADPCCH of the control channel is approximately 256 which isalmost equal to the length of the control data DPCCH of the controlchannel.

Accordingly, the signal power of the control data ADPCCH of the controlchannel is smaller than the signal power of the data DPDCH1 and the likeof the data channel. Further, in the Internet use, because it can beconsidered that the amount of data transferred on uplink is smaller thanthat on downlink, the set number of data channels becomes one in manycases where a link for HSDPA is allocated.

Here, FIG. 21 to FIG. 26 are diagrams showing simulation examples ofCCDF (Complimentary Cumulative Distribution Function) characteristic ofan output waveform from the scrambler 54 when the control data ADPCCH ofthe control channel are assigned on I axis or Q axis in various setnumber of the data channels (using “N” in those figures).

In FIG. 21 to FIG. 26, reference character “I” designates the CCDFcharacteristic when the control data ADPCCH are assigned on I axis, andreference character “Q” denotes the CCDF characteristic when the controldata ADPCCH are assigned on Q axis.

The CCDF characteristic shows the ratio (percentage %) that a momentarypower is in time over an average power. The CCDF characteristic is moreshifted right, the above ratio becomes greater (having a largefluctuation in power). That is, it means that the ratio to take themomentary power of a larger value when compared with the average powerbecomes large. For example, when the set number of the data channels isone (N=1) and the control data ADPCCH of the control channel areassigned on Q axis, the time ratio to take the momentary powerapproximately greater by 3.5 dB of the average power becomes 0.1percentage (%).

In general, a distortion often occurs in the amplifier when a signal ofa larger fluctuation is input. In order to avoid the occurrence of adistortion, it is required to have the linearity in a large powersection. This causes to increase the current consumption.

As can be understood from FIG. 21, when N=1 (only one data channelDPDCH1), the characteristic is greatly changed according to the use of Iaxis or Q axis. In this case, the occurrence to generate the distortionis smaller when the control data ADPCCH are assigned on Q axis.

Similarly, the axis to which the data are assigned is switched accordingto the set number N. It can be understood that the data are assigned onQ axis when N is an odd number, and the data are assigned on I axis whenN is an even number, so that the CCDF characteristic becomes good. Theseresults are equal to the results of the second embodiment.

This means that the above assign method is the most effective method toreduce the distortion from the view point of the CCDF characteristic.

It can be understood that when compared with the case of N=1, the caseof N>1 takes a small distortion because the difference of the signalpowers between I axis and Q axis is not large.

Accordingly, from the view point to keep the balance between the signalpowers on I axis and Q axis and the view point of the characteristic ofthe input signal of the amplifier, there is no problem in practical useeven if the control data ADPCCH of the control channel are assigned on Qaxis together with the control data DPCCH of the control channel.

Thus, when the control data ADPCCH of the control channel are alwaysassigned on Q axis, it is possible to eliminate the distributor 53, thesynthesizer 67, or selectors 58 and 68, as shown in FIG. 17 and FIG. 18.This can achieve the effect to reduce the configuration and size of thecircuit in the mobile station, the base station, and the communicationsystem.

INDUSTRIAL APPLICABILITY

As described above, the mobile station, the base station, thecommunication system, and the communication method according to thepresent invention are particularly suitable for high speed datacommunication to transmit and receive a complex signal in IQmultiplexing.

1. A transmission method, comprising the steps of generating a complexsignal by IQ multiplexing transmission data for a data channel andcontrol data for a control channel; and modulating the complex signalgenerated in the IQ multiplexing and transmitting the modulated complexsignal, wherein when control data for a control channel are added, thecontrol data to be added are assigned to the I axis or the Q axisaccording to a set number for the data channel in the IQ multiplexing.